This invention relates to a method for conveying articles such as empty cans made from thin metal sheet through a conduit to a successive step at a high speed at appropriate intervals by air flow, and also to an apparatus for conveying the articles through the conduit by air flow, receiving the conveyed articles from the conduit and transporting them horizontally.
An apparatus for conveying articles through a conduit by air flow as shown in FIG. 5 is well known, wherein an article to be conveyed is sucked into a conveyor conduit by suction of injected air and then blown upwards, and a blowing pressure in the conduit acts upon a suction inlet for a succeeding article while the preceding article is still in the conduit, and the succeeding article is not placed in the conveyor conduit by suction of injected air, but is sucked into the conduit by suction when the preceding article is discharged from the conduit. More particularly, an L-shaped inlet duct 61 is provided at the lower end of a vertical conveyor duct 60. The bottom wall of the inlet duct 61 is perpendicular or somewhat upwardly inclined to the conveyor duct, and a charge chute 63 is connected to the inlet duct 61 and is somewhat downwardly inclined to the conveyor duct. A blower nozzle 62 is provided at the bottom wall of the L-shaped inlet duct, and connected to a blower. A back flow hole 64 is provided at the joint of the inlet duct 61 and the charge chute 63. A valve 65 is pivotally provided at the upper side of the inlet duct 61 and prevented from movement toward the outside by a stopper 66.
When an article C to be conveyed is moved down to the dotted line position by rolling, the article is placed into the conveyor duct 60 by suction of air injected from the nozzle 62, and then blown upwards. While the article C is still in the duct 60, a reaction or back pressure of a pushing force against the article C exists in the conduit, and consequently the valve 65 is returned to the full line position in turn, restricting the back flow of air and preventing the conveying pressure in the duct, and at the same time a portion of back flow air passes through the valve 65 and is exhausted through the back flow hole 64, and thus there is no suction through the inlet duct. That is, a back pressure acts upon the succeeding article D, thereby stopping the movement of the article D. When the article C is discharged from the duct 60, there is no back flow, and the suction acts again, so that the article D is automatically charged. Thus, a predetermined amount of articles can be always exactly charged into the conveyor duct by one motion by changing the length of the inlet duct 61 appropriately.
However, said apparatus cannot suck the succeeding article to be conveyed, until the preceding article has been discharged from the duct, and thus numbers of the articles to be conveyed in unit time will be disadvantageously limited.